29,911 research outputs found
Radiation Pressure Supported Stars in Einstein Gravity: Eternally Collapsing Objects
Even when we consider Newtonian stars, i.e., stars with surface gravitational
redshift, z<< 1, it is well known that, theoretically, it is possible to have
stars, supported against self-gravity, almost entirely by radiation pressure.
However, such Newtonian stars must necessarily be supermassive. We point out
that this requirement for excessive large M, in Newtonian case, is a
consequence of the occurrence of low z<< 1. On the other hand, if we remove
such restrictions, and allow for possible occurrence highly general
relativistic regime, z >> 1, we show that, it is possible to have radiation
pressure supported stars at arbitrary value of M. Since radiation pressure
supported stars necessarily radiate at the Eddington limit, in Einstein
gravity, they are never in strict hydrodynamical equilibrium. Further, it is
believed that sufficiently massive or dense objects undergo continued
gravitational collapse to the Black Hole stage characterized by z =infty. Thus,
late stages of Black Hole formation, by definition, will have, z >> 1, and
hence would be examples of quasi-stable general relativistic RPSSs. This result
is also supported by with our previous finding that that trapped surfaces are
not formed in gravitational collapse and the value of the integration constant
in the vacuum Schwarzschild solution is zero. Hence the supposed observed BHs
are actually ECOs.Comment: Minor chages in proof. Discusses why the observed BHs are actually
ECOs and Chandrasekhar limit is not applicable to the
Field-control, phase-transitions, and life's emergence
Instances of critical-like characteristics in living systems at each
organizational level as well as the spontaneous emergence of computation
(Langton), indicate the relevance of self-organized criticality (SOC). But
extrapolating complex bio-systems to life's origins, brings up a paradox: how
could simple organics--lacking the 'soft matter' response properties of today's
bio-molecules--have dissipated energy from primordial reactions in a controlled
manner for their 'ordering'? Nevertheless, a causal link of life's macroscopic
irreversible dynamics to the microscopic reversible laws of statistical
mechanics is indicated via the 'functional-takeover' of a soft magnetic
scaffold by organics (c.f. Cairns-Smith's 'crystal-scaffold'). A
field-controlled structure offers a mechanism for bootstrapping--bottom-up
assembly with top-down control: its super-paramagnetic components obey
reversible dynamics, but its dissipation of H-field energy for aggregation
breaks time-reversal symmetry. The responsive adjustments of the controlled
(host) mineral system to environmental changes would bring about mutual
coupling between random organic sets supported by it; here the generation of
long-range correlations within organic (guest) networks could include SOC-like
mechanisms. And, such cooperative adjustments enable the selection of the
functional configuration by altering the inorganic network's capacity to assist
a spontaneous process. A non-equilibrium dynamics could now drive the
kinetically-oriented system towards a series of phase-transitions with
appropriate organic replacements 'taking-over' its functions.Comment: 54 pages, pdf fil
Markov-Yukawa Transversality Principle And 3D-4D Interlinkage Of Bethe-Salpeter Amplitudes
This article is designed to focus attention on the Markov-Yukawa
Transversality Principle (MYTP) as a novel paradigm for an exact 3D-4D
interlinkage between the corresponding BSE amplitudes, with a closely parallel
treatment of and systems, stemming from a common 4-fermion
Lagrangian mediated by gluon (vector)-like exchange. This unique feature of
MYTP owes its origin to a Lorentz- covariant 3D support to the BS kernel, which
acts as a sort of `gauge principle' and distinguishes it from most other 3D
approaches to strong interaction dynamics. Some of the principal approaches in
the latter category are briefly reviewed so as to set the (less familiar) MYTP
in their context. Two specific types of MYTP which provide 3D support to the
BSE kernel, are considered: a) Covariant Instantaneity Ansatz (CIA); b)
Covariant LF/NP ansatz (Cov.LF). Both lead to formaly identical 3D BSE
reductions but produce sharply different 4D structures: Under CIA, the 4D loop
integrals suffer from Lorentz mismatch of the vertex functions, leading to
ill-defined time-like momentum integrals, but Cov LF is free from this disease.
This is illustrated by the pion form factor under Cov LF. The reconstruction of
the 4D wave function is achieved by Green's function techniques. PACS:
11.10 st ; 12.38 Lg ; 13.40.Fn. Keywords: Tamm-Dancoff, Bethe-Salpeter,
Quasi-potentials, Light-front (LF), Markov-Yukawa, 3D-4D Interlinkage, CIA,
Cov-LF, Spectroscopy.Comment: Latex file 38 pp; to appear in the Proceedings of the XXIII Intl.
Workshop on Fundamental Problems in QFT, Protvino, June 200
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